Quick reset induction disk relay



Oct. 1, 1963 M. RIGERT QUICK RESET INDUCTION DISK RELAY Filed May 9,1960 IN V EN TOR. We) Qz lyer' 1 www- United States Patent Ofi 3,105,921Patented Oct. 1, 1963 ice . 3,105,921 QUICK RESET INDUCTEGN DISK RELAYMax Rigert, West Allis, Wis., assignor to McGraw=Edison Company,Milwaukee, Win, a corporation of Delaware Filed May 9, 1960, Ser. No.27,585

2 Claims. (Cl. 3317-58) This invention relates to protective devicesand, more particularly, to a time delay relay having particular but notexclusive application to repeating circuit interrupters.

Repeating circuit interrupters or re-closers are often employed in amain distribution line adjacent the source of power and wherein feederlines radiating from the main line are protected by fuses. Because themajority of faults in distribution systems are temporary in nature andwill clear in a relatively short time, repeating circuit interrupters orreclosers protecting such systems are commonly designed to'execute aseries of rapidly successive opening and reclosing operations upon theoccurrence of afault, so that the period during which the system remainsenergized is shorter than thatnecessary for the fuse elements to melt.If the fault has not cleared after a predetermined number of suchoperations, they are followed by a second series of operations in whichthe interrupter contacts remain closed for a sufiicient length of timeto melt the 'fuse elements. If the fault 1y reset.

The time between successive time delayed operations of a repeatingcircuit interrupter of this type is usually on the order of one to twoseconds. Such delayed operations are accomplished by time delay meanswhich remain inactive during the initial series of operations and whichare made active to retard opening of the switch contacts during thesecond period of operations. One type of time delay device, aninductiontype relay, has been unsuitable for use in a repeating circuitinterrupter because of its inherent inability to be reset betweenopening operations which renders rapidly successive operationsimpossible.

It is an object of the invention to provide an induction type time delayrelay which is usable in a repeating circuit interrupter. a

It is'another object of the invention to provide an induction type relaywhich contacts regardless of the position of the induction These andother objects and advantages of the invention will become more apparentin the detailed description of the invention taken in view of theaccompanying drawing which schematically illustrates an induction typerelay incorporating the instant invention.

In general terms, the invention comprises an induction relay havingelectromagnet means, an operating disc, contact means and releasablecoupling means operable upon the energization of the electromagnet meansto couple the contact means to the operating disc so that the contactmeans is moved toward its closed position. The coupling means is alsooperative upon the de-energization of the electromagnet means to releasethe contact means for rapid movement to its initial position whereby thedevice is reset. When used in a recloser the elect-romagnet means is incircuit with the system being protected and its de-energ-ization occurswhen the contact means closes to complete an energizing circuit to thereclosers switch opening means.

plate.

Referring now to the drawing in greater detail, an in-- duction typerelay 10, according to the instant invention, is shown incorporated in arepeating circuit interrupter '12. The details of circuit interrupter12, which forms no part of the instant invention, are shown in PatentNo. Ryan et al. Relay 10 is coupled phase system 14, which is beingprotected, by means of a three phase current transformer 16. theoccurrence of an unbalanced 14, such as a ground fault in one of ofinduction relay 10 pling and reset assembly 2d automatically couples itto the contact assembly 18. If the fault persists for a predeterminedlength of time, the contact assembly 1 8 will be closed, therebyenergizing the trip coil 21 of repeating circuit interrupter 12 to openits main switch assembly 22. Upon this event, induction relay to isde-energiZed and the coupling and reset assembly 20 automaticallyreturns the contact assembly 18 to its initial position in preparationfor another operation, Means, not shown but which are well known in theart, are also provided for initial series of rapid operations.

More specifically, the induction relay it! is shown to include anoperating disc 23 and an electromagnet assembly 24 having a laminatedcore 25 which the neutral 29 of the three phase current transformer 16.Operating disc 23 is affixed to a shaft 36 for rotation in the air gapseparating thepole pieces 26 and 27 of elcctromagnet 24. In addition, aretarding or damping magnet 31 is disposed with its pole pieces oneither side of operating disc 23 to impart the desired time delaythereto.

rod 3-2 rotatably shaft 39 by means of a bracket member 33 journalled onsaid shaft. tion, a stationary contact 34 is mounted on a guide frame 35having and for guiding it into engagement with fixed contact 34. Thefixed and movable contacts 32 and 34 respectively are shown inconjunction with auxiliary circuitry illustrating how the inductionrelay it? may be incorporated in repeating circuit interrupter 12.. Thisauxiliary circuitry includes an energizing circuit for the trip coil 21of circuit interrupter 12 which is completed between terminals 37 and 33of a power source when the movable contact rod 32 engages the iixedcontact 34. Energizing current for trip coil 21 then flows through thecircuit defined by conductors 4t) and 41, the coil 4-2 of a holdingrelay, conductor 44 the movable contact rod 32, the stationary contact34, and conductors 45, as and 48.

The coupling and reset assembly Ztlincludes a ratchet 52 afiixed toshaft3t? and a pawl 54 rotatably mounted around a reduced portion of a 62 tothe pawl 54. It can be seen, therefore, that when current traverses thecoil of coupling relay 58, its armature 62 will pivot in a clockwisedirection to move the nyloncord 63 toward'the right and rotate pawl 54against the influence of spring 57 and into engagement it will beunderstood that 'also be energized so that its operating a with theteeth of ratchet 5.2. This provides a rigid connection between themovable contact rod 32 and the operating disc 23 so that rotation of thelatter will move contact rod 32, in slot 36 toward the stationarycontact 34. It can be seen, too, that this movement of stationarycontact 32 will be against the restoring force of a torsion spring 67.

Should coil 65 become tie-energized at any time, either before or aftercontact rod engages stationary contact rod 34, spring 57 will rotatepawl 54 out of engagement with the teeth in ratchet 52 thereby freeingbracket and the movable contact rod for rotation to their initialpositions under the influence of torsion spring 67. It can be seen, too,that restoration of the contact rod 32 to its initial or startingposition is independent of the movement of operating disc 23. Therefore,the damping effect of permanent magnet 31 on operating disc 23 has noeflect upon the resetting time of contact assembly 'itl. Hence, thecontact assembly 18 may be immediately reset upon the de-energization ofcoil fi, even though the operating disc 23 remains in its rotatedposition.

Referring again to the auxiliary circuitry associated with inductionrelay li a relay 69 is provided having a. coil connected in thesecondary 29 of three phase current transformer l6 and normally opencontactsYd in circuit between the coil 65 of coupling relay 53 5 and thesource terminals 37 and 38.

From the foregoing discussion it will be apparent that when a groundfault occurs in one of the phases of the system 14 relay 69 will becomeenergized to close its normally open contacts 70 and place the coil 65of coupling relay 5% in circuit with the source terminals 37 and 38.This will rotate armature 62 in a clockwise direction from its phantomposition to its position shown in full so that the nylon cord 63 willoperate to rotate pawl 54 into engagement with the teeth in ratchet 52.Simultaneously the coil 28 of electromagnet 24- will disc 23 will beginrotating in a clockwise direction as shown in the drawing. Because thebracket 33 is now coupled to the shaft 30, the operating rod 32 willbegin moving in slot 36 toward the stationary contact 34-. In thismanner the movable contact rod 32 is coupled to the shaft fit} wheneverthe operating disc 23 rotates.

Should the ground fault disappear before the contact rod 32 engages thestationary contact 34, relay 69 will drop outthereby de-energizing thecoupling relay 5? so that spring 57 disengages pawl 54 from ratchet 52whereby the torsion spring 67 is free to return the contact rod 32 toits initial position. In addition, coil 28 will also be de-energized sothat the rotation of operating disc 23 ceases.

On the other hand, should the ground fault persist until contact rod 32engages the stationary contact 34:, the circuit through the trip coil 23of repeating circuit interrupter 12 is completed. Upon this event, latch7 6 will be rotated out of engagement with the main contacts 22 allowingthem to be opened under the influence of an opening spring 77. Each timethe contacts 22 open, the coil 28 of electromagnet 24 becomesde-energized so that its operating disc 23 ceases to rotate. inaddition, relay 69 drops out to de-energize the coil 65 of couplingrelay 58 enabling springs 57 and 63 to move pawl 54 out of engagementwith ratchet 52 so that the contact rod 32 may return to its initialposition under the influence of torsion spring 67.

The engagement of contacts 32 and 34 also energizes relay 42 which isthen operative to close normally open contacts 74 and thereby complete aby-pass circuit around contacts 32 and 34. This relieves the contactassembly 1% from carrying current during the operation of circuitinterrupter 12.

When the main switch means 22 reaches its fully open position a bridgingbar 79 will close normally open contacts St to place the reclosing coil81 of circuit interrupter 12 in circuit between two phases of the system14. As a result, an armature 82 coupled to the main switch means 22 isattracted upwardly against the influence of opening spring 77 therebyreclosing the main contacts 22 and resetting latch 76. If the groundfault has disappeared while the main switch means 22 was open, thecurrent in the secondary 29 of current transformer 16 will again be zeroand relay 69 and electromagnet 24 will remain deenergized. However,should the fault reappear, the unbalance in three phase currenttransformer 16 will again produce a current in its secondary 29 toenergize the relay 6) and the coil 23 of electromagnet 24. As a result,induction relay It) will begin another timing operation which results intripping of the repeating circuit interrupter 12 in the manner describedabove. If the fault persists after a' predetermined number of suchopening and reclosing operations, usually three, the fault will beconsidered permanent and lockout means (not shown but which are wellknown in the art and which are shown in the above cited patent) willoperate to prevent the reclosure of main switch means 22 until manuallyreset.

Trip coil 21 is also operative upon being energized, and simultaneouslywith the tripping of latch 76, to open contacts 84 so that said tripcoil is not required to carry energizing current during the entireopening operation. It will be understood that contacts 84 will be closedwhen the main switch means 22 is relatched.

The time lapse betweenthe opening and reclosing of contacts 22 is in theorder of one second. As a result, the induction relay Ill must be resetfor another operation within this time. In other words, movable contact32 must return to its initial position while contacts 22 are open sothat the time required for it to retraverse slot 36, should a faultreappear after the reclosure of contacts 22, will be the same for eachsucceeding operation. This is readily achieved because movable contact32 is reset independently of operating disc 23.

While only a single embodiment of the invention is shown and described,other modifications thereof will become apparent once the inventiveconcept is known. It is intended, therefore, to cover in the appendedclaims all such modifications that fall within the true spirit of theinvention.

I claim:

1. In an induction relay, an electromagnet having an air gap and anexciting coil in circuit with an electrical system, a shaft rotatablymounted adjacent said electromagnet, an operating disc mounted on saidshaft for rotation therewith and extending into said air gap, a dampingmagnet associated with said operating disc, said electromagnet beingenergizable upon the occurrence of a predetermined circuit condition torotate said operating disc, coupling means including a ratchet alfixedto said shaft and rotatable therewith, and bracket means rotatablymounted on said shaft, a pawl rotatably mounted on said bracket meansabout an axis parallel to said shaft, fixed and movable contact means,said movable contact means being mounted on said bracket means,electroresponsive means connected to said system and operative upon theoccurrence of said circuit condition to rotate said pawl into engagementwith said ratchet whereby said movable contact is connected to saidoperating disc for movement therewith from an initial position towardsaid fixed contact, said eleotroresponsive means being operative torelease said pawl and said movable contact upon the disappearance ofsaid circuit condition, and biasing means for rotating said pawl out ofengagement with said ratchet and for returning said bracket means andsaid movable contact to their initial position.

2. In an induction relay, a core and an exciting coil in circuit with anelectrical system, an operating disc mounted for rotation in accordancewith the excitation of said cell, bracket means rotatably mountedadjacent said disc and independently thereof, coupling means includingratchet means and co-acting pawl means, one of said ratchet and pawlmeans being afiixed to said disc and the other being mounted on saidbracket means, fixed and movable contact means, said movable contactmeans being mounted on said bracket means, electroresp'onsive meanscoupled to said system and operative upon the occurrence of apredetermined circuit condition to move said pawl means into operativeengagement with said ratchet means whereby said movable contact iscoupled to said operating disc for movement therewith from an initialposition toward said fixed contact, said electroresponsive member beingoperative to release said pawl means and uncouple said movable contactfrom said operating disc upon the disappearance of said circuit con- 6dition, and biasing means for moving said pawl means out of engagementwith said ratchet means and for returning said bracket means and saidmovable contact to their initial positions.

References Cited in the file of this patent UNITED STATES PATENTS1,137,873 Lincoln May 4, 1915 1,658,695 Tnaver Feb. 7, 1928 1,724,390Banch Aug. 13, 1929 2,797,369 Cordray June 25, 1957 FOREIGN PATENTS164,559 Great Britain June 16, 1921

1. IN AN INDICATION RELAY, AN ELECTROMAGNET HAVING AN AIR GAP AND ANEXCITING COIL IN CIRCUIT WITH AN ELECTRICAL SYSTEM, A SHAFT ROTATABLYMOUNTED ADJACENT SAID ELECTROMAGNET, AN OPERATING DISC MOUNTED ON SAIDSHAFT FOR ROTATION THEREWITH AND EXTENDING INTO SAID AIR GAP, A DAMPINGMAGNET ASSOCIATED WITH SAID OPERATING DISC, SAID ELECTROMAGNET BEINGENERGIZABLE UPON THE OCCURRENCE OF A PREDETERMINED CIRCUIT CONDITION TOROTATE SAID OPERATING DISC, COUPLING MEANS INCLUDING A RATCHET AFFIXEDTO SAID SHAFT AND ROTATABLE THEREWITH, AND BRACKET MEANS ROTATABLYMOUNTED ON SAID SHAFT, A PAWL ROTATABLY MOUNTED ON SAID BRACKET MEANSABOUT AN AXIS PARALLEL TO SAID SHAFT, FIXED AND MOVABLE CONTACT MEANS,SAID MOVABLE CONTACT MEANS BEING MOUNTED ON SAID BRACKET MEANS,ELECTRORESPONSIVE MEANS CONNECTED TO SAID SYSTEM AND OPERATIVE UPON THEOCCURRENCE OF SAID CIRCUIT CONDITION TO ROTATE SAID PAWL INTO ENGAGEMENTWITH SAID RATCHET WHEREBY SAID MOVABLE CONTACT IS CONNECTED TO SAIDOPERATING DISC FOR MOVEMENT THEREWITH FROM AN INITIAL POSITION TOWARDSAID FIXED CONTACT, SAID ELECTRORESPONSIVE MEANS BEING OPERATIVE TORELEASE SAID PAWL AND SAID MOVABLE CONTACT UPON THE DISAPPEARANCE OFSAID CIRCUIT CONDITION, AND BIASING MEANS FOR ROTATING SAID PAWL OUT OFENGAGEMENT WITH SAID RATCHET AND FOR RETURNING SAID BRACKET MEANS ANDSAID MOVABLE CONTACT TO THEIR INITIAL POSITION.